*{
    margin:0px;
    padding:0px;
}
.box{
    width:302px;
   height:302px;
    box-sizing:content-box;
    padding:3px;
    border:1px solid yellow;
    position:relative;
}
.dl{
    width:100px;
    height:100px;
    background:pink;
}
.box .er{
    position:relative;
    left:200px;
    top:-100px;
}
.box .si{
    position:relative;
    left:200px;
    top:-100px;
}
.box .wu{
    position:relative;
    left:100px;
    top:-300px;
}
a:link{
    text-decoration:none;
}
a{
    display:block;
    line-height:100px;
    text-align:center;
}
.dl:hover{
    background:blue;
}